And yesterday, the Guardian revealed that the stealth jet fighter might be actually using US technology:

(The Guardian) A Chinese stealth fighter jet that could pose a significant threat to American air superiority may borrow from US technology, it has been claimed.

Balkan military officials and other experts said China may have gleaned knowledge from a US F-117 Nighthawk that was shot down over Serbia in 1999.

"At the time, our intelligence reports told of Chinese agents crisscrossing the region where the F-117 disintegrated, buying up parts of the plane from local farmers," said Admiral Davor Domazet-Loso, Croatia's military chief of staff during the Kosovo war. "We believe the Chinese used those materials to gain an insight into secret stealth technologies ... and to reverse-engineer them."

The Nighthawk was downed by a Serbian anti-aircraft missile during a bombing raid on 27 March 1999. It was the first time one of the fighters had been hit, and the Pentagon blamed clever tactics and sheer luck. The pilot ejected and was rescued.

A senior Serbian military official confirmed that pieces of the wreckage were removed by souvenir collectors, and that some ended up "in the hands of foreign military attaches". Efforts to get comment from China's defence ministry and the Pentagon were unsuccessful.

Parts of the F-117 wreckage, including its left wing, cockpit canopy, ejection seat, pilot's helmet and radio, are exhibited at Belgrade's aviation museum. Zoran Milicevic, deputy director of the museum, said: "I don't know what happened to the rest of the plane. A lot of delegations visited us in the past, including the Chinese, Russians and Americans ... but no one showed any interest in taking any part of the jet."

Zoran Kusovac, a Rome-based military consultant, said the regime of the former Serbian president Slobodan Milosevic routinely shared captured western equipment with its Chinese and Russian allies. "The destroyed F-117 topped that wish-list for both the Russians and Chinese," Kusovac said.

China's multi-role stealth fighter known as the Chengdu J-20 made its inaugural flight on 11 January, revealing dramatic progress in the country's efforts to develop cutting-edge military technologies. It is at least eight or nine years from entering service.

Russia's Sukhoi T-50 prototype stealth fighter made its maiden flight last year and is due to enter service in about four years. It is likely that the Russians also gained knowledge of stealth technology from the downed Nighthawk.

But then, this doesn't really come as a surprise neither. It might actually something less dark than technology stealing, given that US companies (and generally speaking Western economies) are more than happy to make massive technology transfer in order to gain contracts that rather meaningless in comparison. Yet, this has been what the Siemens, Areva, Airbus, Boeing, Alsthom, and so forth have been doing during the past 5-10 years.

As China strives for leadership in the world’s most advanced industries, it sees commercial jetliners — planes that may someday challenge the best from Boeing and Airbus — as a top prize.

And no Western company has been more aggressive in helping China pursue that dream than one of the aviation industry’s biggest suppliers of jet engines and airplane technology, General Electric.

On Friday, during the visit of the Chinese president, Hu Jintao, to the United States, G.E. plans to sign a joint-venture agreement in commercial aviation that shows the tricky risk-and-reward calculations American corporations must increasingly make in their pursuit of lucrative markets in China.

G.E., in the partnership with a state-owned Chinese company, will be sharing its most sophisticated airplane electronics, including some of the same technology used in Boeing’s new state-of-the-art 787 Dreamliner.

For G.E., the pact is a chance to build upon an already well-established business in China, where the company has booming sales of jet engines, mainly to Chinese airlines that are now buying Boeing and Airbus planes. But doing business in China often requires Western multinationals like G.E. to share technology and trade secrets that might eventually enable Chinese companies to beat them at their own game — by making the same products cheaper, if not better.

The other risk is that Western technologies could help China play catch-up in military aviation — a concern underscored last week when the Chinese military demonstrated a prototype of its version of the Pentagon’s stealth fighter, even though the plane could be a decade away from production.

The first customer for the G.E. joint venture will be the Chinese company building a new airliner, the C919, that is meant to be China’s first entry in competition with Boeing and Airbus.
[...]
G.E., which said it had briefed the commerce, defense and state departments on details of the deal, acknowledges that pairing up with a Chinese firm is a delicate dance. But because the commercial aircraft market in China is expected to generate sales of more than $400 billion over the next two decades, it is not a party the company is willing to miss.
[...]
Several other American companies have also been chosen as suppliers for the C919 aircraft, providing power generators, fuel tanks, hydraulic controls, brakes, tires and other gear. The roster of United States suppliers includes Rockwell Collins, Honeywell, Hamilton Sundstrand, Parker Aerospace, Eaton Corporation and Kidde Aerospace.

In fact, the corporate competition for contracts on the C919 became a “frenzy,” said Mark Howes, president of Honeywell Aerospace Asia Pacific. The Chinese government, he said, had made it clear to Western companies that they should be “willing to share technology and know-how.”
[...]
“I think you’re naïve if you don’t take into account that you could be standing up a future competitor,” Mr. Statler said. Any company in a global business is in a race, he added, and staying ahead is the only defense. “At the end of the day, our technologies and processes have to continue to improve,” Mr. Statler said. “It comes down to who can innovate faster.”